This invention relates to a change-speed gear system for use in an automatic transmission. More particularly, this invention relates to a change-speed gear system which allows the automatic transmission to be compact in size and alternatively used for various types of vehicular drive systems such as front-engine and front-wheel drive, front-engine and rear-wheel drive, rear-engine and rear-wheel drive and four-wheel drive.
A number of automatic transmissions have been used in vehicles having various types of drive systems, such as front-engine and front-wheel drive (FF), front-engine and rear-wheel drive (FR), rear-engine and rear-wheel drive (RR), and four-wheel drive (4D).
However, it has appeared impossible to interchange the conventional automatic transmissions, for example, from a front-engine and rear-wheel drive to a front-engine and front-wheel drive, because of the varying constructions of the various parts built therein. This is also true with the application of conventional automatic transmissions from front-engine and rear-wheel drive to front-engine and rear-wheel drive or four-wheel drive.
In addition, the manufacture of a new automatic transmission for a different type of drive system results in many disadvantages from the viewpoint of cost, assembly, parts control and servicing. Any application of an existing type of automatic transmission to a different type of drive system has dictated the additional use of separate and new parts and devices. As can be seen, problems are encountered in either adapting an existing type of automatic transmission or utilizing a new automatic transmission to use in a different type of vehicular drive system.
Accordingly, it is a primary object of this invention to provide a change-speed gear system for use in an automatic transmission, which can be easily modified to alternative use in any one of the FF, RR, FR and 4D vehicular drives.
A further object of this invention is to eliminate the costly and time-consuming retrofitting of an automatic transmission to another type of vehicular drive system or the manufacture of a new automatic transmission for another type of vehicular drive system.
Another object of this invention is to provide a change-speed gear system for use in an automatic transmission, which is compact in size and allows a large degree of design variation for an internal combustion engine and a torque convertor.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the descriptions, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing objects and in accordance with the purpose of the invention, as embodied and broadly described herein, the change-speed gear system of the invention comprises a change-speed gear system for use in an automatic transmission comprising a center output shaft having actuating opposite ends; a hollow input shaft coaxially disposed around one end of the output shaft; a hollow intermediate shaft coaxially disposed around the output shaft; first and second planetary gear mechanisms, each mechanism including a sun gear, a ring gear, and a planetary carrier rotatably supporting the planetary pinion, the sun gears being secured to the intermediate shaft, and the planetary carrier and the ring gear, respectively, of the first and second planetary gear mechanisms being secured to the output shaft; first and second selectively actuatable clutches, each clutch having a drivable portion and a driving portion engageable with the said drivable portion, the driving portions of the clutches being coupled to the input shaft and the drivable portions of the first and second clutches being respectively coupled to the ring gear of the first planetary gear mechanism and to the intermediate shaft; and first and second selectively actuatable brakes, each brake having a non-movable portion and a movable portion engageable with the non-movable portion, the movable portions of the first and second brakes respectively coupled to the intermediate shaft and to the planetary carrier of the second planetary gear mechanism; and wherein selective actuation of the first and second clutch means and the first and second brake means establishes three forward-speed gear ratios and one reverse-speed gear ratio.
Preferably, the change-speed gear system further includes a unidirectional clutch means for preventing movement in one direction of the planetary carrier of the second planetary gear mechanism.
In one preferred embodiment of the change-speed gear system, power is transmitted from the end of the output shaft adjacent the input shaft such as in the application of the change-speed gear system to a vehicular FF or RR drive.
In still another preferred embodiment of the changespeed gear system, power is transmitted from the end of the output shaft opposite the input shaft, such as in the application of the change-speed gear system to a vehicular FR drive.
In yet another preferred embodiment of the change-speed gear system, the power is transmitted from both opposing ends of the output shaft such is in the application of the change-speed gear system to a vehicular 4D drive.
The invention consists in the novel parts, constructions, arrangements, combinations and improvements shown and described. The accompanying drawing, which is incorporated in and constitutes a part of this specification, illustrates one embodiment of the invention and, together with the description, serves to explain the principles of the invention.